This is a request for a Mentored Clinical Scientist Development Award (K08). The candidate proposes to use this award to develop a research career in treatment and services research for individuals with drug use disorders. The goals of the career development plan are to (1) develop the methodologic expertise required to test hypotheses derived from specific clinical populations in studies of the general population, (2) gain greater expertise in understanding specific predictors of and barriers to obtaining treatment among individuals with drug use disorders, and (3) develop the skills necessary to implement a specific study of treatment services utilization based on results gained from the proposed studies conducted during the award period. These career development goals are in concert with the research plan, which will consist of three studies, each designed to build on increasing knowledge as acquired during the award period. The overall aim of the research plan is to extend and amplify our understanding of the impact of sociodemographic characteristics, psychiatric comorbidity, severity and type of drug use disorder, and insurance status on patterns of treatment services utilization in individuals with drug use disorders. A series of three studies will use data from a general population sample derived from the national Comorbidity Study and the Mental Health Supplement of the Ontario Health Survey to determine the impact of these factors on: 1. Whether individuals with drug use disorders obtain treatment services, 2. When individuals with drug use disorders obtain treatment services, and 3. What type of treatment services are used by individuals with drug use disorders. This research plan will explore three central hypotheses: 1. Sociodemographic characteristics and psychiatric comorbidity will be the important predictors of treatment services use among those with less severe drug use disorders. 2. Sociodemographic characteristics and psychiatric comorbidity will be less important predictors of treatment services use than insurance status among those with more severe drug use disorders, and 3. Patterns of treatment services utilization will vary by specific drug type.